Add the method isOpaque() to SkImage

src/image/SkImage_Raster.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImage_Base.h"
 #include "SkImagePriv.h"
 #include "SkBitmap.h"
@@ skipping 48 matching lines @@
     virtual const void* onPeekPixels(SkImageInfo*, size_t* /*rowBytes*/) const SK_OVERRIDE;
     virtual bool getROPixels(SkBitmap*) const SK_OVERRIDE;
 
     // exposed for SkSurface_Raster via SkNewImageFromPixelRef
     SkImage_Raster(const SkImageInfo&, SkPixelRef*, size_t rowBytes);
 
     SkPixelRef* getPixelRef() const { return fBitmap.pixelRef(); }
 
     virtual SkShader* onNewShader(SkShader::TileMode, SkShader::TileMode) const SK_OVERRIDE;
 
+    virtual bool isOpaque() const SK_OVERRIDE;
+
 private:
     SkImage_Raster() : INHERITED(0, 0) {}
 
     SkBitmap    fBitmap;
 
     typedef SkImage_Base INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
@@ skipping 117 matching lines @@
 }
 
 SkImage* SkNewImageFromPixelRef(const SkImageInfo& info, SkPixelRef* pr,
                                 size_t rowBytes) {
     return SkNEW_ARGS(SkImage_Raster, (info, pr, rowBytes));
 }
 
 SkPixelRef* SkBitmapImageGetPixelRef(SkImage* image) {
     return ((SkImage_Raster*)image)->getPixelRef();
 }
+
+bool SkImage_Raster::isOpaque() const {
+    return fBitmap.isOpaque();
+}